1. Field of the Invention
This invention relates to a rotation detecting device for sensing a rotation direction using a magneto-electric converter device.
2. Description of the Related Art
As shown in Patent Document 1, a rotation detecting device of related art using a magneto-electric converter device has a magnetic moving body shaped to cause changes in a magnetic field, a magnet disposed facing the magnetic moving body and magnetized in the rotational axis direction of the magnetic moving body, and a processing circuit part with four magneto-resistance segments constructed integrally and disposed with a predetermined spacing in the rotational axis direction of the magnetic moving body. A pair of magneto-resistance segments adjacent in the rotation direction of the magnetic moving body form a first bridge circuit, and another pair of magneto-resistance segments adjacent in the rotation direction of the magnetic moving body form a second bridge circuit.
A fixed voltage is impressed on the first bridge circuit, and resistance value changes of the magneto-resistance segments caused by changes in the magnetic field are converted into voltage changes. A resulting voltage-converted signal is amplified by an amplifier circuit and inputted to a first comparator circuit. A signal produced by the first comparator circuit comparing this with a predetermined voltage Vref1 is converted into a final output by an output circuit and is also inputted to a D terminal of a D flip-flop circuit. Similarly a fixed voltage is applied to the second bridge circuit and resistance value changes of those magneto-resistance segments caused by changes in the magnetic field are converted into voltage changes. The resulting voltage-converted signal is amplified by an amplifier circuit and inputted to a second comparator circuit. A signal produced by the second comparator circuit comparing this with a predetermined voltage Vref2 is inputted to a CL terminal of the D flip-flop circuit. The output signal of the D flip-flop circuit is converted by an output circuit into a rotation direction detection output.
Patent Document 1: JP-A-2002-90181 (paragraphs 0018 through 0029 and FIGS. 1 through 3).
The related art rotation detecting device has had the problem that, because it is constructed as described above, when deviations arise in the comparison level Vref1 of the first comparator circuit and the comparison level Vref2 of the second comparator circuit in the signal processing circuit part 3, or when deviations arise in the amplifier circuit outputs, it is not possible for rotation direction detection to be effected accurately.